Scalable Coding of video refers to compression techniques that result in a compressed bitstream in which one or more subsets of the whole bitstream can be decoded, at reduced quality (such as reduced resolution, frame rate, or bit-rate). Scalable coding techniques have been present in most video compression standards, including MPEG-1, MPEG-2 and MPEG-4. Examples of scalable video coding include compression of an HD bitstream in which an SD subset can be decoded, or compression of a 60 Hz bitstream in which a 30 Hz subset can be decoded.
A particular application of scalable video compression arises because many TV operators are planning to deploy 1080P @ 60 Hz video services in the next few years. This format is what is used by many of the high-end consumer HD displays currently being purchased. The fact that this format is scanned progressively eliminates the need for de-interlacing within the consumer display, and the 1080 line format offers higher resolution than the 720P format.
The Joint Video Team (JVT) of the ISO/MPEG group and the ITU-T have developed a Scalable Video Coding (SVC) draft standard based on H.264/AVC. According to the draft, an SVC encoder outputs a base layer stream which is of lower quality than the original, and at least one enhancement stream. A receiver can choose to decode only the base layer stream, or it may choose to decode the base layer stream in combination with one or more of the enhancement streams to reconstruct a higher quality picture sequence. The SVC draft includes a great deal of flexibility for scalable coding of video, and its compression tools offer high efficiency. However, the complexity of the SVC technology is high, both for encoders and decoders. A need therefore exists to develop a satisfactory mechanism for implementing an SVC codec cost-effectively.